希瓦氏奥奈达菌MR-1还原针铁矿的实验研究及地球化学意义

Reduction of Goethite by Shewanella Oneidensis MR-1 and Its Geochemical Implication

本文实验研究了希瓦氏奥奈达菌株(Shewanella oneidensis MR-1,以下简称MR-1)在pH为中性的厌氧条件下还原针铁矿的过程,探讨了MR-1菌异化还原针铁矿的动力学特征。采用邻菲罗啉分光光度法检测了反应前后溶液中铁含量的变化,利用扫描电子显微镜、粉晶X射线衍射和激光拉曼光谱分析了针铁矿及其还原产物的形貌特征和物相组成。结果表明,针铁矿在厌氧条件下可被MR-1还原,生成磁铁矿、菱铁矿等次生矿物。本文认为针铁矿的微生物异化还原过程以直接接触机制为主,同时存在间接还原机制;溶液中的Fe2+与CO32-、SO42-等沉淀生成菱铁矿等次生产物,同时部分Fe2+、Fe3+离子可吸附于矿物表面,甚至能引起矿物相的转化,两者共同构成了针铁矿的次生分解路径。

Based on interaction experiments between Shewanella oneidensis strain MR-1（MR-1） and synthesized goethite,this paper studied the solubility and bioreduction process of goethite,as well as secondary minerals under circum neutral pH.O-Phenanthroline spectrophotometry was employed to analysis changes of soluble iron in solution;scanning electron microscope-energy dispersive spectrometer（SEM-EDS） was applied to investigate mineral surface morphology;X-ray diffraction（XRD） and laser Raman spectrometer were used to determine mineral phases of initial mineral and final products during the interaction period.Results indicate that goethite is bioreducible under anaerobic conditions by MR-1,with secondary mineralization accompanying reduction processes.We drew a conclusion that direct contact dominated and indirect reduction mechanism coexisted the course of goethite bioreduction,and direct secondary precipitation from solution.It is also found that ion adsorption on secondary products potentially induced further mineral transformation.